Eficiência da aplicação de defensivos químicos e inoculante de longa vida, combinados ou não, em sementes de soja

Abstract

Soy is not a native crop in Brazil, therefore, nitrogen-fixing bacteria are not found naturally in Brazilian soils. Thus, strategies for the supply of nitrogen to the soybean culture, whether by mineral sources, inoculation or co-inoculation, must be evaluated in order to have a higher productivity. This study aimed to evaluate the application of chemical pesticides and long-life inoculants, in mixtures or not, under different conditions of storage and cultivation in controlled environments. Two experiments were conducted: laboratory - a completely randomized design was used, in a factorial scheme 8 x 7, with four replications, with treatments consisting of eight combinations of industrial seed treatment (TIS), using chemical pesticides (fungicide / insecticide) and long-life inoculant, alone or in mixtures, being: {T1 - control; T2 - fungicide (MaximAdvanced); T3 - insecticide (Fortenza); T4 - long life inoculant (Nitragin CTS 200); T5 - mixture of fungicide / insecticide products (MaximAdvanced + Fortenza); T6 - long life fungicide / inoculant (MaximAdvanced + Nitragin CTS 200); T7 - long life insecticide / inoculant (Fortenza + Nitragin CTS 200); T8 - mixture of long-life fungicide / insecticide / inoculant products (MaximAdvanced + Fortenza + Nitragin CTS 200)}, stored for two months, with evaluations every ten days (10; 20; 30; 40; 50 and 60 days); greenhouse - a completely randomized design was used, in an 8 x 2 factorial scheme, with three replications. The treatments, consisted of the eight combinations of applications, mentioned in the laboratory test, however, it was carried out in pots containing soils from two cultivation areas (area of first year of cultivation and area with several years of cultivation). In the first trial, evaluations of physiological quality of seeds were carried out during storage; in the second test, the chlorophyll index and nodulation capacity were evaluated. It is concluded that the use of fungicide and insecticide chemicals and their combinations impaired the physiological quality of soybean seeds. The seeds treated with long-life inoculant, in isolation, proved to be efficient in relation to nodulation, vegetative growth and physiological quality. In addition, they showed efficiency in relation to vegetative growth and plant nodulation. However, in the laboratory there was a reduction in physiological quality during storage. The treatment of seeds and soybean inoculation applied in isolation or not, did not influence the nodulation process, regardless of the history of the cultivation area. Soya beans, regardless of the type of treatment received, can be stored for a period of 40 days for commercial purposes.